Method for hot rolling plate

ABSTRACT

In the method of hot rolling steel plate, the leading edge of the plate emerging from the roll is turned slightly, to prevent undesirable jamming against objects and the ensuing cobble. This slight turn in the edge is effected toward the larger roll when the ratio of the diameters of the rolls is between about 1.0015 to 1.007.

United States Patent Lloyd J. Fenstermaker Baldwin Borough, Pa.

May 8, 1970 Dec. 21, 1971 United States Steel Corporation inventor Appl. No. Filed Patented Assignee METHOD FOR HOT ROLLING PLATE [56] References Cited UNlTED STATES PATENTS 274,525 3/1883 Smith 72/227 813,141 2/1906 Cowles... 72/166 Primary ExaminerLowe1l A. Larson Attorney-John R. Pegan ABSTRACT: In the method of hot rolling steel plate, the leading edge of the plate emerging from the roll is turned slightly, to prevent undesirable jamming against objects and the ensuing cobble. This slight turn in the edge is effected toward the larger r011 when the ratio of the diameters of the rolls is between about 1.0015 to 1.007.

. pn qd sla ms-w This invention relates to a method for controlling the direction of the leading edge of steel plate during hot rolling.

More particularly, this invention relates to a method for preventing the leading edge of the plate from catching and jamming against objectson the rolltable h In many instances during the rolling of steel plate, as for example, on tandem hot strip and plate mills, there is a tendency for the leading edge of the work piece, upon emerging from the roll stand, to turn downwardly and foul itself, e.g. in one of the many cavities in the roller table between stands. The cob-i -ble that ensues, not only results in a total loss of the piled metal, but may also cause severe damage to the mill. This problem could be alleviated if the leading edge of the plate. could be provided with a slight upward turn, so that it can be properly directed, e.g. by use of suitable guide bars, to the, next pass in the mill. It is well known (see, for example, E. Tanaka et al, Curling 8L Bowing of Rolled Strips, Trans, 1.? Inst. Metals, Volume 4, (1963), pages 124-133) that the un-: balanced residual stresses in cold rolled strip caused by the use 1 of upper and lower work rolls of different diameters will produce a curl along the whole length of the rolled strip,g wherein the strip will curl to the smaller roll side. It has now. been found, somewhat contrary to what might be expected in, view of prior knowledge, that in the hot rolling of strip and plate, the leading edge of the work piece will curve to the; larger roll side if the diameter of the larger roll is from about; 1.00 l 5 to about l .007 times the diameter of smaller roll. It is therefore an object of this invention to provide a method whereby the leading edge of hot rolled plate may be directed as it leaves the forming rolls.

It is another object of this invention to provide a method for preventing the leading edge of hot rolled plate from jamming and fouling against roller table cavities.

The above and other objects will become more apparentl when read in conjunction with the following examples and the The following examples were all performed on a seven;

stand, 100 inch mill, in which the 06 and 07 stands performed i between thetable rolls, causing buckling which hindered movement of the plate through the subsequent leveler, parting shears, and to the stacking bed. To alleviate this situation,

embossed) In all of the above cases, a good tumup was achieved for the leading edge of the plate. This leading edge was then directed to the underside of an I beam guide lbar, anchored between the mismatch roll stand and the subsequent stands, to prevent the plate from rising, thus insuring that the plate will be in correct position for entry to the next roll. A variety of entry or delivery pass guides, well known in the art, may be employed.

. Thus, by the method of this invention, the leading edge of hot rolled plate may be quantitatively turned in a desired direction, so that it can be accurately fed to a subsequent operation, thereby eliminating costly damage to the mill and the work piece. The exact amount of the turn imparted must be determined empirically, since it is affected by such variables as percent reduction, thickness of the plate, material being worked, temperature of rolling and degree of roll mismatch.

While the above description has been directed to imparting an upward turn to the leading edge of plate, it will, of course,

be obvious that the same principle can be employed to provide a down turn to the edge. In the latter case, the bottom roll will be the larger of the two.

I claim:

1. In the process of hot rolling steel plate, a method for causing the leading edge of the plate emerging from the rolls to turn slightly in a desired direction, which comprises rolling the plate between rolls in which the diameter of the roll (R,) to which it is desired to have the edge turn towards, is from about 1.00l5 to about 1.007 times the diameter of the roll (R from which the leading edge turns away.

2. The method of claim 1, wherein the leading edge of the plate is prevented from fouling in a portion of the roller table, by causing said edge to turn slightly upward, wherein roll (R,) is employed as the upper roll.

3. The method of claim 2, wherein the diameter of the rolls employed are of the order of 27 inches, and the upper roll is from about 0.040 to 0.200 inches larger in diameter.

4. The method of claim 1, wherein the plate being rolled is an alloy steel and roll (R is an embossing roll, provided with I a pattern of depressions.

various mismatch rolls were employed with the larger roll on top, as shown in table I.

5. The method of claim 4, wherein the slightly turned leading edge of the plate is mechanically guided to the next pass. 

2. The method of claim 1, wherein the leading edge of the plate is prevented from fouling in a portion of the roller table, by causing said edge to turn slightly upward, wherein roll (R1) is employed as the upper roll.
 3. The method of claim 2, wherein the diameter of the rolls employed are of the order of 27 inches, and the upper roll is from about 0.040 to 0.200 inches larger in diameter.
 4. The method of claim 1, wherein the plate being rolled is an alloy steel and roll (R1) is an embossing roll, provided with a pattern of depressions.
 5. The method of claim 4, wherein the slightly turned leading edge of the plate is mechanically guided to the next pass. 